The new arch callback should manage NMIs that usually cause KGDB to enter. That is, not all NMIs should be enabled/disabled, but only those that issue kgdb_handle_exception().
We must mask it as serial-line interrupt can be used as an NMI, so if the original KGDB-entry cause was say a breakpoint, then every input to KDB console will cause KGDB to reenter, which we don't want.
Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- include/linux/kgdb.h | 3 +++ kernel/debug/debug_core.c | 14 +++++++++++--- 2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h index c4d2fc1..7800cce 100644 --- a/include/linux/kgdb.h +++ b/include/linux/kgdb.h @@ -240,6 +240,7 @@ extern void kgdb_arch_late(void); * hardware breakpoints. * @correct_hw_break: Allow an architecture to specify how to correct the * hardware debug registers. + * @enable_nmi: Manage NMI-triggered entry to KGDB */ struct kgdb_arch { unsigned char gdb_bpt_instr[BREAK_INSTR_SIZE]; @@ -252,6 +253,8 @@ struct kgdb_arch { void (*disable_hw_break)(struct pt_regs *regs); void (*remove_all_hw_break)(void); void (*correct_hw_break)(void); + + void (*enable_nmi)(bool on); };
/** diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c index 0557f24..17e073c 100644 --- a/kernel/debug/debug_core.c +++ b/kernel/debug/debug_core.c @@ -672,6 +672,10 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) { struct kgdb_state kgdb_var; struct kgdb_state *ks = &kgdb_var; + int ret = 0; + + if (arch_kgdb_ops.enable_nmi) + arch_kgdb_ops.enable_nmi(0);
ks->cpu = raw_smp_processor_id(); ks->ex_vector = evector; @@ -681,11 +685,15 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs) ks->linux_regs = regs;
if (kgdb_reenter_check(ks)) - return 0; /* Ouch, double exception ! */ + goto out; /* Ouch, double exception ! */ if (kgdb_info[ks->cpu].enter_kgdb != 0) - return 0; + goto out;
- return kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); + ret = kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER); +out: + if (arch_kgdb_ops.enable_nmi) + arch_kgdb_ops.enable_nmi(1); + return ret; }
int kgdb_nmicallback(int cpu, void *regs)